We have obtained several putative clones of myosin heavy chain from both lambda gt10 and lambda gtll cDNA libraries of human lymphocytes. Initial attempts to establish their authenticity by sequencing and northern analysis is underway. We also intend to sequence other myosin heavy chain tryptic fragments, especially the peptide containing the protein kinase C phosphorylation site, from which additional oligonucleotide probes will be derived. Other strategies for obtaining appropriate probes and libraries may also need to be considered. When the cDNA and/or gene have been cloned we anticipate using this information to study nonmuscle myosin expression and structure.